re. upper boost limit for stock MC-1 internals?

[Swann, Benjamin R. (BSWANN)]

<snip>[I know that some listers have experimented beyond the standard, 1.8
bar, chipped boost levels.  Also, the reason 1.8 bar is a common level of
chipped boost is because it's been proven not to break anything.

I was wondering just how conservative this increase is.  I know that there
are basically three things that limit boost:  pinging, excessive heat in the
combustion chamber, and compressor efficiency.  Is there anything else?]  
<snip>
[Thanks,

Ken]

Ken,

1.8 may be conservative, but I have not been able to go much more without
risking detonation.  I'm currently set to hit around 18PSI ~ 2.2Bar.  At
that level, I know I need to be very careful with the Octane I'm using,
especially on hot days.  I know there are more things I need to consider
before reasing the bar(pun intended) any farther.  This mostly equates to
time and $$.

Regards,

Ben
http://www.homestead.com/Ben_Swann/boostin.html